1. Field of the Invention
The present invention relates to an anti-reflection film, which is arranged for the purpose of preventing reflection of external light on the surface of a window, a display, and the like. Particularly, the present invention relates to an anti-reflection film, which is arranged on the surface of a display such as a liquid crystal display (LCD), a CRT display, an organic electroluminescence display (ELD), a plasma display (PDP), a surface-conduction electron-emitter display (SED), and a field-emission display (FED). Particularly, the present invention relates to an anti-reflection film, which is arranged on the surface of a liquid crystal display (LCD). Among these, the present invention relates to an anti-reflection film, which is arranged on the surface of a transmission type liquid crystal display (LCD).
2. Description of the Related Art
In general, displays are used in the environment onto which external light and the like are incident regardless of whether they are used indoors or outdoors. This incident light such as external light is reflected on the display surface so that a displayed image is interfered with the reflected image and the quality of display decreases. Hence, it is necessary to provide a display surface and the like with an anti-reflection function, and further, improvements of the anti-reflection function along with introductions of other extra useful functions are being demanded.
In general, an anti-reflection function is realized by forming an anti-reflection layer having a multilayer structure repeating high refractive index layers and low refractive index layers made of a transparent material such as metal oxide on a transparent substrate. The anti-reflection layer including this type of multilayer structure can be obtained by a dry coating method such as chemical vapor deposition (CVD) and physical vapor deposition (PVD).
In the case where the anti-reflection layer is formed by a dry coating method, while there is an advantage of fine thickness controllability of a low refractive index layer and a high refractive index layer, there is also a problem of low productivity due to a limitation of a deposition process performed in a vacuum chamber, which is unsuitable for mass production. Thus, wet coating methods, which use a coating liquid for forming an anti-reflection layer and can provide a large display, produce continuously, and reduce costs, attract attention as a method of forming an anti-reflection layer.
In addition, in the anti-reflection film in which such anti-reflection layer is arranged on the transparent base, the surface thereof is relatively flexible. Thus, a method is generally used in which a hard coat layer resulting from curing of an acrylic-based material is arranged in order to give hardness to the surface, and an anti-reflection layer is formed on the hard coat layer. This hard coat layer is provided with a high level of surface hardness, luster, transparency, and abrasion resistance due to the acrylic-based material.
In the case where an anti-reflection layer is formed by a wet coating method, the anti-reflection layer is produced by coating at least a low refractive index layer on such hard coat layer resulting from curing of such ionization radiation curable materials, and the wet coating method has a merit of inexpensive production in comparison with a dry coating method, and thus, this type of anti-reflection film is widely distributed in the market.
<Patent document 1>: JP-A-2005-202389.
<Patent document 2>: JP-A-2005-199707.
<Patent document 3>: JP-A-H11-92750.
<Patent document 4>: JP-A-2007-121993.
<Patent document 5>: JP-A-2005-144849.
<Patent document 6>: JP-A-2006-159415.
<Patent document 7>: JP-A-2007-332181.